Evaporator



Aug. 30, 1938. NlBBs 2,128,469

'EVAPORATOR Original Filed Aug. 8, 1934 5 Sheets-Sheet 1 f/zz/eniiow: 5 /2651" #62655 I wag/.

Aug. 30, 1938. E. NIBBS 2,128,469

' EVAPORATOR Original Filed Aug. 8, 1934 s Sheets-Sheet 2 E. NIBBS EVAPORATOR'v Aug. 30, 1938.

Original Filed Aug.. 8, 19:4

3 Sheets-Sheet 3 Patented Aug. 30, 1938 UNITED STATES PATENT OFFlCE EVAPORATOR Original application August 8, 1934, Serial No.

738,922. Divided and this application November 27, 1935, Serial No. 51,771

Claims.

This invention relates to evaporators for submarine boats, and has to do with means for evapcrating sea water or water of flotation so as to produce steam useful within the hull for various 5 purposes, including the obtaining of drinking water for the personnel of the boat.

It is known, in submarine boats, to evaporate sea water and condense the resulting steam and fresh water vapor so as to obtain water suitable for drinking purposes. This may be accomplished by electrical heating means deriving energy from the boat storage battery, by independent boilers within the hull, or by boilers heated by the exhaust gases from the main and/or auxiliary internal combustion engines within the hull. In all of these cases, according to present practice, the boiler or evaporator is installed within the hull, which is objectionable as taking up valuable space. A further objection to having the boiler within the hull is that it radiates considerable heat resulting in greatdiscomfort to the crew, even when the evaporator is insulated, and providing thick and eificient insulation upon the evaporator with a view to avoiding radiation of heat therefrom further increases the bulk of the evaporator, so that it occupies additional space within the hull.

It is an object of my invention to provide a boiler or evaporator of simple and efficient con struction disposed exterior of the hull and capable of being operated from the interior thereof, thereby conserving valuable space within the hull while avoiding the above noted objections to having the boiler or evaporator in the interior of the boat. It is also an object to provide a boiler of the character stated of light weight, which can be readily disassembled for cleaning and repairs, and which has associated therewith means for quick flooding of the various spaces of the boiler or evaporator and associated parts. A further object is to provide a boiler of this character adapted to be heated from a source of heat within the hull, conveniently the main and/or auxiliary internal combustion engines, this boiler being suitable for disposition between the deck of the superstructure and the top of the hull while avoiding objectionable heating of the superstruc ture deck. Further objects and advantages of my invention will appear from the detail description In the drawings:-'-

Figure 1 is a central longitudinal sectional view through an evaporator embodying my invention, certain parts being shown in elevation, this view being taken substantially in the plane of line |--l of Figure 2;

Figure-2 is a sectional View taken substantially in the plane of line 2-2 of Figure 1;

Figure 3 is an end view of the boiler, looking at the inlet end thereof for the exhaust gases from the internal combustion engine within the hull of the submarine boat;

Figure 4 is a side view of a boiler embodying my invention as applied to a submarine boat, the latter being shown fragmentarily and in section, parts being broken away and shown in section with certain parts shown in elevation, this view being semi-diagrammatic.

In my co-pending application for evaporator for submarines, Serial No. 738,922, filed August 8, 1934, which matured into Patent No. 2,025,524 I have disclosed an evaporator as applied to a submarine boat. The evaporator of my present invention is similar to that disclosed in my copending application and the instant application, which is a continuation in part of said co-pending application, has to do more particularly with the evaporator per se.

The boiler or evaporator includes an inner muffier unit M and an outer water jacket unit W, the latter, though preferred, not being essential in all cases, as will hereinafter appear.

The muffler unit comprises a mufiler tube 5 conveniently of rectangular cross-section and open at both ends. This tube is welded or otherwise suitably secured, at its outer end, to an outer closure plate or head 6. The inner end of tube 5 is welded to a relatively thick flange l bolted or otherwise suitably secured to an inner closure plate or head 8, the latter being detachable from flange 1. The plates 6 and 8 are of circular shape and the latter plate is welded or otherwise suitably secured in the inner end of a cylindrical shell 9 which extends about tube 5 and defines therewith a water space and a steam space thereabove. The outer end of shell 9 is welded or otherwise suitably secured to a relatively thick annular flange 8a bolted to plate 6. Circular swash plates 10 are secured upon tube 5 and fit snugly within shell 9. These plates H] are provided with suitable openings for flow of the water therethrough and serve to prevent objectionable surge of the water within shell 9, incident to sudden or abrupt movements of the evaporator caused by pitching and rolling of the submarine boat, with which the evaporator is associated, when traveling on the surface in rough weather.

The normal water level within shell 9 is indicated by the line a:,:z: in Figures 1 and 2. Tube 5 is provided with a plurality of thimble-shaped hollow projections or tubes ll extending thereinto from opposite sides thereof and disposed in staggered relation, these tubes or projections ll constituting baffles for the hot exhaust gases discharged into tube 5. It will be noted that the thimble-shaped tubes I! are closed at their inner ends and open at their outer ends into shell 9 below the normal water level therein, that is, into the water space within this shell. Preferably, vertical bafile plates I? are suitably supported between the swash plates It a short distance from the outer ends of the thimble tubes ll, these bafiies l2 promoting circulation and quick heating of the water within shell 9.

A steam take-off pipe I5 is disposed within shell 9 adjacent the top thereof, in steam space 16 above the normal water level. The pipe 55 is closed at its inner end, extends through plate 6, and has its outer end welded in a fitting ll bolted to the outer face of plate 6, this fitting providing means for connecting a steam conducting pipe to the steam take-off pipe. Pipe I5 is slotted at its upper portion for reception of steam and exclusion of water, in a known manner. Preferably, the steam take-01f pipe is disposed within a housing I8 extending from plate 6, the inner end of this housing being closed and the upper wall of shell 9 constituting the top of the housing. Housing l8 has its upper portion slotted as shown for admission of steam and is provided, at its lower portion, with suitable openings for drainage therefrom of water into the shell 9. As clearly shown in Figure 1, the slots of housing I8 are staggered relative to the slots of pipe l5, better to prevent entry of water into the latter. Conveniently, pipe l5 seats in curved supports l9 of angle cross-section suitably secured in housing l8, though any other suitable means may be provided for supporting the steam take-01f pipe. The swash plates H] are, of course, suitably notched out at their upper portions to accommodate the housing III, as shown in Figure 2. Each of these plates is also preferably provided, at its lower portion, with a notch 20 to facilitate blowing of sediment out of the shell 9, as will hereinafter appear.

Plate 6 is provided with an opening 2! into shell 9 at the bottom of the latter. A fitting 22 is bolted to the outer face of plate 6 and provides means for connecting a blow-off pipe 23 to opening 2|. A fitting 24 is bolted to the outer face of plate 6 adjacent one side thereof and below the water level within shell 9, this fitting 24 providing means for connecting a water supply pipe 25 to the interior of shell 9. Two additional fittings 26 and 2! are bolted to the outer face of plate 6 below and above the water level in shell 9, respectively, and provide means for connecting tubes 28 and 29, respectively, to the interior of shell 9. Preferably, plate 6 is suitably bored and threaded for reception of a plurality of zinc plugs 39 which project beyond the inner face of this plate into the interior of shell 9. These plugs, being susceptible to corrosion, localize the corrosive effect of the sea water within the shell 9, which reduces corrosion of the latter.

The water jacket comprises two concentric cylinders 35 and 36 spaced apart and defining therebetween a water space 37. The cylinder 35 is welded at one end to a flange 35 which seats against the inner fact of flange 8 and the adjacent end of cylinder 36 is welded to a. relatively thick ring 38, the latter seating against the inner face of plate 9 and being bolted or otherwise removably secured thereto. The inner cylinder 35 is provided, at its otherend, with a closure plate 39 to which is welded a frusto-conical element 40 defining an outlet opening for the exhaust gases from muffler tube 5. Plate 39 is spaced away from plate 8 of shell 9 and defines with the latter a gas receiving space All. The other end of cylinder 36 is welded to a relatively thick annular flange 42 the inside diameter of which is slightly greater than the outside diameter of cylinder 35. Flange 52 is bolted to a head or plate 43 spaced outwardly from plate 39 and provided with an outlet opening 44% which registers with the outlet opening of element 39. Plate 43 is shaped, about opening id, to provide a seat which snugly receives the outer portion of element 49, the latter being Welded to plate 93. Adjacent the lower portion of element 99, an inwardly projecting deflecting element 15 is welded to plate 39 and is disposed to direct a. portion of the gases flowing from tube 5 downward into space M and thence into gas circulating space 45 between shell 9 and cylinder 35, the latter being spaced from the former, as shown, to permit of flow of a portion of the exhaust gases about shell 9 in contact therewith. An outlet nipple M is secured through plates 39 and 43, conveniently by welding to these plates, and opens into space 4| at the top thereof. An arcuate baffle 48 projects from the inner face of plate 39 and extends below and to either side of nipple 47. This bafile serves to direct the gases from the upper portion of space 46 into nipple 41, and thence to atmosphere. This promotes circulation of the gases about shell 9. A drainage nipple 49 is suitably secured through plates 43 and 39, conveniently by welding to these plates, and opens into the cylinder 35 adjacent the bottom thereof for draining water from this cylinder, as will hereinafter appear.

A. flanged water inlet fitting 59 opens into water space 31 between cylinders 35 and 36 for normally supplying water to this space, this tting being welded to the latter cylinder. Fitting 50 is provided with a flanged neck 5! intended for connection to supplementary water supply means for assuring flooding of the water jacket when the boat dives or is submerged. Cylinder 39 is further provided, at the top thereof, with a flanged outlet fitting 52 welded to cylinder 36 about a suitable opening through the latter.

The boiler or evaporator so far described comprises the water jacket unit and the mufller unit previously referred to. The muffler unit is carried by plate 6 and may be inserted into and withdrawn from the water jacket unit by removal of the bolts which secure ring 38 to plate 6. The inner end of the mufiler unit is spaced from plate 39 of the water jacket unit, as above, it also being noted that plate 8 is spaced from baflies 45 and 48, as shown in Figure 1. This accommodates independent expansion and contraction of the two units lengthwise thereof and relieves the structure, as a whole, of objectionable stresses from this cause. Preferably, suitable blocks 53 are welded or otherwise suitably secured to the inner face of cylinder 35 and provide means for supporting and centering shell 9 therein. Preferably, the ends of the blocks toward plate 6 are beveled at 54, as shown, to facilitate insertion of the muffier unit. I also prefer to provide suitably spaced blocks 55 welded or otherwise suitably secured in cylinder 36 and aligned with blocks 53, to assist in supporting the muffler unit within the water jacket unit.

The mufiier unit and the water jacket unit may be assembled and disassembled in the manner above stated. Access may be had to the interior of the mufller unit, for cleaning, repairs, or other purposes, by removing the bolts securing plate 8 to flange 1, after which the bolts securing flange 8 to plate 6 may be removed, and the muffler tube, together with swash plates l and the steam take-oil pipe I5, may be withdrawn as a unit from shell 9. This gives ready access to all parts of the muflier unit structure. Access may be had to the interior of the water jacket, after removal of the mufiier unit, as above, by removing the bolts securing head or plate 43 to flange 4-2 of cylinder 36, the latter being then moved endwise away from plate 43 and from about cylinder 35. It will be understood that, in the structure of the boiler or evaporator, suitable gaskets and packings may be provided where desired or necessary. These have been omitted, for clearness of illustration, and as being obvious.

In Figure 4 I have illustrated an evaporator in accordance with my invention applied to a submarine boat B comprising a hull a and a superstructure b having a deck 0 above the top of the pressure hull a. The boat itself is of known construction and need not be illustrated nor described in detail.

One or more internal combustion engines are suitably disposed within hull a and each of these engines is provided with a cylinder water jacket, in a known manner. Cooling water, commonly water of flotation, is supplied under pressure to the cylinder jacket of the engine in a suitable manner, as by means of a pump driven by the engine and having its intake connected to a sea valve opening to the sea through the hull, the discharge of the pump being connected to the water jacket of the engine. An axhaust pipe 69 is connected to the exhaust manifold of the engine for conducting the hot exhaust gases therefrom. This pipe is provided with a water jacket 6! which communicates with the water jacket of the engine in a known manner for receiving water therefrom. The engine and the means for supplying cooling water thereto and to the water jacket of the exhaust .pipe are of known construction and need not be illustrated nor further described here. The general arrangement is disclosed more fully in my above identified copending application.

Exhaust pipe 60 is connected, at its upper end, to a valve fitting 62 disposed at the inner face of the top of the hull, this fitting being provided with a water jacket 63. Fitting 62 is aligned with a fitting 64 disposed at the outer face of the top of the hull and provided with a water jacket 65. Fitting 62 accommodates an inboard valve 66 for opening and closing the passage from exhaust pipe 60 into this fitting. Valve 66 is of known type and is operated, in a known manner, by means (not shown) disposed within the hull. An outboard valve 61, of known type, is mounted in fitting 64for controlling the passage therethrough, and is operated, by known means (not shown), from within the hull, in a known manner. The

, fittings 6?! and 64 are disposed in register with upper end, with a flanged outlet neck 68 to which is bolted one end of an exhaust horn 69. This horn is of rectangular cross-section and flares toward plate 6 of the evaporator, to which the other end of the horn is bolted about the rectangular opening through this plate corresponding to the adjacent end of exhaust tube 5.

Water jacket 6| of exhaust pipe 60 is connected to water jacket 63 of fitting 62 in a suitable manner, as by means of short passages 19 and ll formed in pipe 60 and neck 62 of fitting 62, respectively, and disposed in register one with the other, it being understood that any suitable number of these passages may be provided. Valve 66 has associated therewith a water jacket 12. This water jacket 72 and water jacket 63 of fitting 62 are connected by pipes 13 and '14, respectively, to a Y member F5 from thestem of which extends a pipe 1'6 provided with valves TI and 18 disposed inboard of the hull. A branch pipe 19, provided with a valve Bil disposed outboard of the hull, but operated from within the latter, connects pipe 16 to water jacket 65 of fitting 64. It will be noted that valve 6? has associated therewith a water jacket 8! in direct communication with water jacket 65 of fitting 64. Pipe 16 is further provided with a valve 82 exterior of the hull, but operable from within the latter, and a branch pipe 83, connected to pipe T6 at opposite sides of valve 82, provides a shunt around the latter. Branch pipe 83 is provided with a valve 84 exterior of, but operable from within, the hull. Pipe 16 is connected, by means of pipe 25 and fitting 24, to the interior of the boiler or evaporator for supplying water thereto. Water jacket 65 of fitting G4 is connected, by a tube 86, to an elbow 81 secured to the lower end of fitting 50. Tube 86 serves normally to supply water to the water jacket.

In the normal use of the evaporator, when the boat is on the surface, valves 66 and 6'! are open, as shown, and valves ll, 18, Bl] and 84 are opened, valve 82 being closed. By adjusting valve 80, to restrict more or less the pipe 19, the desired pressure within pipe 16, for delivering water into the evaporator, may be obtained. The valve 80 is normally open to a sufiicient extent to permit flow of water through pipe #9 into water jacket 65 while also assuring flow of waterthrough pipe TB. By adjusting valve 84, the rate of feed of water to the evaporator may be regulated as desired. Opening valve 82 permits free flow of water into the evaporator, which may be desirable for washing out the latter or for other purposes. While water is being thus delivered into the evaporator, water is also being delivered to the water jacket, by means of tube 86, and is discharged from the water jacket through fitting 52 and a discharge conduit 99 attached to this fitting and disposed to discharge the water overboard. The hot exhaust gases are delivered into the muffler tube and flow therethroughinto space 4!, a portion of these gases being deflected into space 46 so as to circulate about the shell 9, as above described, and the remainder of the gases being discharged through a conduit 9! bolted to the outer face of plate 43, this conduit being open to the atmosphere. The heat from the hot exhaust gases is, to a large extent, absorbed by the water within the evaporator, by means of tube 5 and the baffle elements l I thereof, so that this water is quickly heated to boiling temperature and generates steam and water vapor which collects within space l'6 above the normal water level.

A steam conducting pipe 92 is connected, at

its upper end, by means of a T 93, and fittin II, to the outer end of steam take-off pipe I5. The lower end of pipe 92 is connected to a cruciform pipe fitting 90, to the lower end of which is connected a steam conducting tube 95 which extends into hull a and is there provided with two valves 96 and 91. The other end of tube 95 is connected to the inlet of a condenser 98 of known type disposed within the hull, from which the condensate is withdrawn through a take-off pipe 99. This condenser 98 is cooled in a suitable manner, conveniently by the water of flotation, for which purpose the condenser may be provided with water inlet and outlet pipes I00 and IOI, respectively. Conveniently, the cooling water may be supplied to the condenser from the pump which supplies water to the water jacket of the engine, or in any other suitable manner. The steam generated within the evaporator is led to the condenser where it is condensed to provide pure water suitable for drinking purposes and other uses by the personnel of the boat. During normal use of the evaporator, the valves 96 and 9! are, of course, open.

A safety or pressure relief valve I02, of known type, is mounted at the upper end of T 93. Neck 5| of fitting is connected, by a pipe I03, to one side of fitting 94. A valve 88, operable from within the hull, is interposed in pipe I03, this valve normally being closed. An inwardly opening pressure responsive valve I04, of known type, is connected to the other side of fitting 94. This latter valve is to assure quick flooding of the water jacket, when diving or submerging, as will be explained presently. Blowout pipe 23 is provided with a valve I05 operable from within the hull, which valve is normally closed. If desired, however, valve I05 may be kept slightly open for drainage from shell 9 of salt and other sediment which may collect at the lower portion thereof, it being understood that in this case valve 89 is kept open suificiently to supply water to the evaporator at a rate sufficient to compensate for the continual slight discharge of water through pipe 23. Tubes 28 and 29 pass into the hull and are connected, through valves I06 and I07 and I08 and I09, respectively, to tubes 28 and 29*, respectively, the latter tubes being connected to a water level indicator or gauge ill] of known type disposed within the hull. This provides convenient means for observing the water level within the evaporator.

Preparatory to submerging or diving, the engine is stopped and the exhaust stack valves I56 and 61 are closed, it being understood that pipe may lead from the exhaust manifold of a single engine or may be connected to the exhaust manifolds of a plurality of engines. Shortly thereafter, as soon as the engine water supply stops, valves II and I8 are closed and valves I05, I01, I08 and I09 are also closed, either at this time or earlier, valve 88 is opened, and valve I95 is fully opened. During submergence of the boat, water of flotation flows freely through pipe 23 into the evaporator so as to fill completely shell 9, the space at the upper portion of this shell being vented through pipe 92 and tube 95 into the condenser 98. As soon as the evaporator has thus been completely filled with water, the valves 99 and 91 areclosed. Water also enters freely through the exhaust conduit 9| and nipples 4? and 49 into spaces M and 56, tube 5, horn 99 and the upper portion of fitting 64 above valve 61, in the closed position of the latter; Also, valve I04 opens under the influence of the water pressure, when submerged, so that the water of flotation flows through pipe I03, neck EI and fitting 50 into the interior of the water jacket and water may also enter the water jacket through fitting 52 and the associated conduit 90. In this manner, all of the spaces of the evaporator, including the evaporator unit and the water jacket unit, are quickly flooded so as to be completely filled with the water of flotation, when the boat dives or submerges. This renders it unnecessary to construct the evaporator sufficiently strongly to withstand submergence pressure and, accordingly, the evaporator, including the water jacket, may be of relatively light weight, which is an important consideration. Since the tube 86 communicates with the interior of the water jacket, through the fitting 50, the pressure within. water jacket 65 of fitting 64, and within the pipes and tubes exterior. of the pressure hull a, and the pressure exterior of these parts, when the boat is submerged, are equalized. Accordingly, none of these parts need be of exceptionally heavy construction, which is advantageous as rendering the structure, as a whole, of relatively light weight.

If desired, known means may be provided for venting air from the Water jacket when submerging. This means may be of any suitable or preferred type. It is also contemplated to provide the water jacket with suitable areas of zinc to localize the corrosive action of the salt water flowing therethrough.

When the boat emerges after diving, water drains from spaces 4| and 46 through the conduit M and nipple 49, fitting 64, above the closed valve Bl, horn 69 and muffler tube 5 draining into space II. The boiler or evaporator drains through the blow-out pipe 23 until the desired normal water level is reached, at which time valve I05 is closed. Valves 66 and 61 may then be opened, as may valves TI, I8, 96, 91, I09, I01, I08 and I09, valve 88 being first closed. The engine may then be set into operation and the evaporator again used in the manner previously described. It will be noted that the lower portion of fitting 92 is of bowl-shape and is provided with a screw plug I I I. This provides convenient means for draining from fitting 62 any slight amount of water which may collect therein, such as water which may flow into this fitting from the upper portion thereof when valve 6! is opened after the boat emerges at the surface from a dive.

What I claim is:

1. In an evaporator for use with submarine boats, a horizontal muffier tube open at its ends for reception and outlet of hot exhaust gases from an internal combustion engine, a. horizontal shell enclosing said muffler tube and defining therewith a water space and a steam space thereabove, a steam take-off pipe communicating with said steam space, a cooling water jacket enclosing said shell in spaced relation. thereto and defining therewith a gas receiving space, and means establishing communication between the outlet end of said tube and said space.

2. In an evaporator for use with submarine boats, a horizontal muffler tube open at one end for reception of hot exhaust gases from an internal combustion engine and open at its other end for escape of said gases, 2. horizontal shell enclosing said muffler tube and defining therewith a water space and a steam space thereabove, a steam take-off pipe communicating with said steam space, and a water jacket enclosing said shell, the latter and said tube being spaced at said other end of said tube from the adjacent end of said water jacket and free therefrom for expansion and contraction independently of said water jacket.

3. In an evaporator for submarine boats, a mufiler unit comprising a muflier tube and a shell surrounding said tube and provided with end closure plates attached to said tube and having openings aligned with the ends thereof, and a water jacket enclosing said unit and having one end attached thereto and its other end free from and spaced outwardly beyond said unit to accommodate independent expansion and contraction of the latter, said other end of said water jacket having an exhaust gas outlet opening.

4. In an evaporator for submarine boats, a muiller unit comprising a mufller tube: and a shell surrounding said tube and provided with end closure plates attached to said tube and having openings aligned with the ends thereof, and a water jacket enclosing said unit and having one end secured to one end of said unit and its other end free from and spaced outwardly beyond the other end of said unit to accommodate independent expansion and contraction of the latter, said other end of said water jacket having an exhaust gas outlet opening, said one end of said water jacket being detachablysecured to the closure plate at said one end of said unit.

5. In an evaporator for submarine boats, a muffler unit comprising a muffler tube and a shell surrounding said tube and provided with end closure plates attached to said tube and having openings aligned with the ends thereof, and a water jacket enclosing said unit in spaced relation thereto and having one end secured to said unit and its other end adjacent and spaced from the other end of said unit, said other end of said water jacket having an exhaust gas outlet opening, said one end of said water jacket being detachably secured to the closure plate at said one end of said unit.

6. In an evaporator for use with submarine boats, a muffler tube, a shell extending about said tube in spaced relation thereto, swash plates mounted on said tube and fitting within said shell, a closure plate for one end of said shell removably secured to one end of said tube and having an opening into the latter, a water jacket enclosing said shell and having one end spaced from said closure plate and provided with an opening communicating with the opening of said plate, and a closure plate secured to the other end of said tube and shell, said second closure plate being removably secured to the other end of said water jacket and provided with an opening to the other end of said tube.

7. In an evaporator for use with submarine boats, a muffler tube, a shell enclosing said tube and defining therewith a water space and a steam space thereabove, a valve controlled water supply pipe communicating with said shell, a valve controlled steam take-off pipe communicating with said steam space, a valve controlled blowo-fi pipe communicating with said shell, a water jacket enclosing said shell and having an exhaust gas outlet opening communicating with the outlet of said tube, said jacket being provided with a water outlet open to the atmosphere and a Water inlet member, a water supply tube connected to said inlet member, a valve controlled flood pipe connecting said water inlet member and said steam take-off pipe, and an inwardly opening pressure responsive valve controlling said flood pipe.

8. In an evaporator for use with submarine boats, a mufiler tube, a shell enclosing said tube and defining therewith a water space and a steam space thereabove, a valve controlled water supply pipe communicating With said shell, a valve controlled steam take-01f pipe communicating with said steam space, a valve controlled blowoff pipe communicating with said shell, a water jacket enclosing said shell and spaced therefrom with its end adjacent the inner end of said shell spaced from the latter and provided with an exhaust gas outlet opening, said water jacket and said shell defining a gas circulating passage extending about said shell and opening freely into the space between the inner end of the latter and the adjacent end of said jacket, the latter being provided with a water outlet open to the atmosphere and a water inlet member, a water supply tube connected to said inlet member, a valve controlled flood pipe connecting said water inlet member and said steam take-off pipe, and an inwardly opening pressure responsive valve controlling said flood pipe.

9. In an evaporator for use with submarine boats, a muffler tube, a shell extending about said tube in spaced relation thereto, a closure plate for one end of said shell removably secured to one end of said tube and having an opening into the latter, a Water jacket enclosing said shell and having one end spaced from said closure plate and provided with an opening communicating with the opening of said plate, and a closure plate secured to the other end of said tube and said shell, said second closure plate being removably secured to the other end of said water jacket and provided with an opening to said other end of said tube.

10. In an an evaporator for use with submarine boats, a muffler tube, a cylindrical shell extending about said tube in spaced eccentric relation thereto, two concentric cylinders extending about said shell concentrically therewith, said cylinders being spaced apart and defining a water jacket extending at one end beyond one end of said shell, inner and outer closure plates secured in said inner and outer cylinders at said end of said jacket, said plates being secured together in spaced relation and defining an outlet opening into said inner cylinder, said outer closure plate being removably secured to said outer cylinder and the adjacent end thereof defining an opening of a size to accommodate said inner cylinder, said inner plate being spaced from one end of said shell, a closure plate for said one end of said shell removably secured to the adjacent end of said tube and having an opening thereinto, and a closure plate for the other end of said shell secured to the other end of said tube and having an opening thereinto, the last mentioned closure plate being removably secured to said other end of said shell and to the other end of said outer cylinder, the other end of said inner cylinder being free from said last mentioned closure plate.

ERNEST NIBBS. 

